Family XXI. Cichlid^e. 



213 



Head 2-f ; depth 2% to 2%; D. xv or xvi, 10 or 11 ; A. v or vi, 7 

 or 8. Body elongate, compressed; head large, mouth large and 

 strong; maxillary 2~/ z in head; the lower jaw the longer; teeth in the 

 outer series of both jaws enlarged, not numerous ; lips thick, no frenum 



FlG. 69. CiCHLASOMA ISTLANUM (Jordan & Snyder). 

 No. 6150, Leland Stanford Jr. University. 



in some specimens, a partial one in others; mandible 2,1 in head; 

 snout 3-? ; interorbital convex, 2% in head; preorbital 3X; post- 

 orbital 2]/ A ; diameter of eye 4^; cheeks with about 6 rows of scales; 

 eighth dorsal spine 3 ]A, in head ; the last spine 2 % to 3 ; middle rays of 

 dorsal and anal produced, sometimes reaching past middle of caudal 

 fin; pectoral fin i| in head; ventral fins with rays produced into a 

 filament in larger specimens, the tips reaching second anal spine; in 

 specimens where the rays are not produced the tips of the caudal fin 

 do not reach origin of the anal; caudal fin rounded, the least depth of 

 caudal peduncle 2^3 in head, its length slightly less than depth. 



Color nearly black to a light brownish, each scale with an oblong 

 dark spot in the center; traces on the smaller and lighter individuals 

 of about 7 dark vertical bars; smaller individuals (less than 4 inches) 

 have a black spot on middle of the side, one at base of caudal and one 

 at upper edge of gill opening; dorsal, caudal, and anal fins spotted with 

 black; in some specimens the spots on scales very prominent, forming 

 longitudinal lines on lower half of the body. Length about 12 inches. 



This species is very abundant in the Balsas Basin, and at present 

 is the only member of the family known from it. It is quite variable 

 in color, some specimens from Yautepec being nearly black on the lower 

 half of the body, or with scattered black blotches. The nuchal hump 

 is developed quite well in males 7 inches in length. In the speci- 

 mens from Yautepec the ovaries are little .developed and give no 



